Splash guards or mud guards are often used on vehicles to block debris that may be thrown into the air by the vehicle's rotating tires. In fact, splash guards are mandated on many vehicles, such as Class 8 vehicles. FIG. 5 is a schematic illustration of conventional splash guards 10 mounted on a Class 8 vehicle, such as semi-trailer 12. As best shown in FIG. 6, the splash guard 10 includes a thin planar body 14 defining a forward facing planar surface 16 (see FIG. 6) and a rearward facing surface 18. The perimeter of the forward facing surface 16 is formed by sharp leading edges 20. The splash guard 10 may be secured at its top end to the vehicle 12 in a conventional manner such that the forward facing surface 16 extends vertically at a spaced distance behind the vehicle's tire(s) 22. The planar, forward facing surface 16 is suitably positioned relative to the associated tire(s) to deflect debris, such as gravel, pebbles, mud, water, or the like, that is thrown into the air by the rotating tires 22.
In general, the planar surfaces 16 of the splash guards 10 are perpendicular to the direction of motion of the vehicle 12, thereby restricting air flow and generating drag forces on the vehicle. Turning to FIG. 6, there is shown a partial plan view of the conventional splash guard 10 of FIG. 5 mounted on one side of the vehicle 12 behind tires 22. As depicted, the tires 22 are arranged in a dual configuration, having an outside tire 22a located proximate the exterior of the vehicle 12 and an inside tire 22b located proximate the interior of the vehicle 12. As the tires 22 rotate in a clockwise direction, the vehicle 12 moves in the direction indicated by arrow A. As such, air flows past the exterior of the vehicle 12, including the outside tire 22a, in a substantially opposite direction of vehicle motion, as indicated by arrows B.
Although much of the surface area of the splash guards 10 is shielded by the tires, as can be seen in FIG. 5, some of the air flows against the splash guard 10 and is displaced by the splash guard 10, thereby generating drag forces.